Marine scientists and engineers recently set free a robot called
Sirius to explore the ocean floor at Ningaloo in WA. This
Autonomous Underwater Vehicle (AUV), equipped with high resolution
cameras and sonar and the ability to navigate on its own, has allowed
them to gain unparalleled insights into deep water environments. The
joint expedition between scientists from the Australian Institute of
Marine Science (AIMS) and the University of Sydney's Australian Centre
for Field Robotics (ACFR) was designed to explore the suitability of
AUVs for environmental monitoring.
"This has been a major step forward in understanding the deeper
water seabed communities that occur around Ningaloo. In the past,
ecologists have relied on trawl gear and tools that are fixed to the
support vessel by cables to collect information about the seascape at
great depths" says expedition leader, Max Rees from AIMS. "The fact
that the vehicle does not require a tether gives us a great deal of
flexibility in the areas we can work".
BHP Billiton is providing AIMS with research funds to enhance
marine knowledge of the North West Cape and Ningaloo Reef and it is
this corporate support for science that is largely responsible for
bringing the AUV to Ningaloo. The strong corporate patronage is
enabling projects based on cutting edge marine technologies to
compliment and extend the impact of the Governments’ marine science
initiatives at Ningaloo under WAMSI.
Sirius was designed for detailed surveys of underwater
environments in depths of up to 700 metres. It uses an onboard
computer system and an array of instruments to navigate just metres
above the seabed. The vehicle scans the seafloor creating bathymetric
sonar maps while collecting thousands of high-resolution digital
images per hour. It is programmed prior to deployment to follow a
survey pattern while its progress can be monitored on the surface via
an underwater acoustic modem, in this case from the AIMS Research
Vessel Cape Ferguson.
Dr Stefan Williams from ACFR says, "Last year engineering trials
were conducted at Ningaloo and on the Great Barrier Reef but this is
the vehicle’s first major scientific survey expedition."
Speaking from the ship in the last days of the expedition Max Rees
said, "An unexpected discovery was the abundance of life clinging to
the very tops of the steep deepwater canyons, where the continental
shelf drops away not far from Ningaloo’s shallow reef. Many of the
sponges and deepwater corals that were photographed may be new to
science. Also of interest were fields of mound features that were
observed on the shallower seabed plateau. We suspected the mounds were
there, although their cause remains a mystery, but have now been able
to see them in spectacular detail."
In all, half a million images were collected on 20 dives, with the
vehicle operating within canyons in depths of up to 250m. Captured
directly onto onboard computers, the individual stereo images can be
used to measure minute features of the seabed with unmatched clarity
and detail. The researchers are assembling these images into mosaics
that enable them to observe larger scale patterns in the data.
"Stitched together the digital photos will effectively provide
photographic maps of the seabed, giving an idea of the distribution of
benthos as if the overlying deep ocean had been removed," Dr Williams
says.
"For AIMS, this expedition has played a critical role in exploring
the use of robots in underwater research. Robotic technology is a very
effective way to run controlled surveys of steep walled canyons and
other complex terrain. The vehicle uses a variety of sensors to figure
out where it is and to follow its planned mission. The data collected
can then be geo-referenced to allow scientists to assess how deep sea
communities are distributed as a function of depth or seabed
composition. For industry this technology may be used to ensure the
environment is adequately surveyed before projects such as underwater
pipelines are commissioned. Worldwide, companies that lay deep sea
cables and conduct geophysical and hydrographic surveys are
increasingly relying on AUVs," Dr Williams says.
"The next step is to look at repeating surveys to assess changes in
these habitats over time. Given the current deployments, we can send
the vehicle down to have another look in six months or a year. To
observe really fine scale change will require that the robots have the
ability to recognise parts of our survey when we return." Parallel
research into data management and artificial intelligence are part of
the R & D program. "We are working on automated methods to deal
efficiently with the massive volume of data we are collecting. This is
important to allow us to quickly show the scientists the most
interesting images or seafloor structures in the areas we have
surveyed. It also raises the possibility of allowing the vehicle to
decide during its mission when it is seeing something of particular
interest. It might then be instructed to go in and have a closer look
when it sees something out of the ordinary." explains Dr Williams
Footage and photos will be made available on request.
